I think the issue that most people won't gather up the will to do aerobic exercise after they are mentally exhausted -- even that they know it works to some extent.
Following this, I believe, without scientific proof, that genius (or others who can contribute significantly more than other people) have their mind wired completely different from other people. For example, I know people who are super smart, super energetic, and (in the context of OP article) can switch between tasks efficiently. They don't seem to need cooldown, they always have the will to do something as long as they know it's good for them. In one sentence, they are more like machines.
I wonder if there is a way for ordinary people to achieve that "machine-like" mentality. I'm curious to learn from your experience if you are able to grow from a "weak-minded" people to a "strong-will" one, however painfully. So far I haven't seen one example.